1. Field of the Invention
The present invention relates to an autofocus camera provided with a rangefinding device of a multi-beam type, and to a method for regulating such a rangefinding device, more particularly to an autofocus camera in which the operating state of the rangefinding device can be checked in an inspection during production, and to a method for correcting an error in the measurement performed by the rangefinding device.
2. Description of Related Art
Multi-beam type rangefinding devices are widely used in modern compact cameras. Rangefinding devices of this type have a light projector for projecting a plurality of light beams sequentially and horizontally relative to a photographic scene, and a light receiver for receiving the light beams reflected by the photographic scene so as to detect their incident positions. As a light source for the light projector, LEDs (light emitting diodes) emitting near infrared light are used arranged in a line. As the light receiver, a PSD (semi-conductor position sensitive detector) is used. When there are a plurality of principal objects in the photographic scene, rangefinding data are calculated for each of the respective rangefinding light beams. An optimum rangefinding datum is selected from among them a distance datum for determining the position at which a taking lens is to be set.
Among the optimum rangefinding data, there are provided a near distance selection, a medium distance selection, and the like. According to the near distance selection, the rangefinding datum of the nearest object is selected as being optimum. Therefore, the multi-beam rangefinding device has the advantage of ease in focussing the principal object, without the inconvenience of performing focus-lock or the like, even when the principal object is situated outside the center of the photographic scene, or when a plurality of persons standing in a line are photographed.
In the process of assembling an autofocus camera, an inspection is performed after the rangefinding device is incorporated in the camera body, to determine whether the rangefinding device can be properly operated. In such an inspection, a test object positioned at a predetermined object distance is used for adjusting the mounting positions of the light projector and the light receiver while measuring the position of the taking lens in correspondence with each LED, so that light beams emitted from all the LEDs generate rangefinding data of an equal value for the same test object.
In this conventional inspecting method, there are problems of low efficiency in operation and possible differences in the respective LEDs as regards precision of rangefinding. This is because it is necessary to measure the taking lens setting position for each of the rangefinding light beams in order to adjust the positions of the light projector and the light receiver, whereas another operation of rangefinding is required for checking the completion of adjustment.